Surtr is apparently a battle-loving individual who loves to fight strong opponents. He once fought against the "Gods" and wiped them out. He is not above giving praise to opponents. he can become quite frustrated with his current weakened condition, most likely stemming from his pride as a warrior.
Surtr does get along with his master quite well. When he attacks South and he gets annoyed that he cannot beat her, East reminds him that his "fists are not that powerless" which calms him down. It is also worth noting that Supporters have to choose (and be willing) to obey their masters, and forcing a Supporter to serve you would take up enormous amounts of mana. Seeing as how East in currently in a weakened state and Surtr still serves her, it is reasonable to believe that they are close enough that he agreed to be her Supporter and loyal enough to stay as such, even when she lost a huge amount of her power.
He is also quite protective of East, and notes that while it would be a shame to kill a powerful person who still has potential to grow, he will never permit those who attack his master to survive. He also valued her life over his pride and chose to leave a battle he could easily win so that she would no longer suffer from having to supply him mana.
Surtr is one of the only being powerful enough to be a supporter of one of the Four Great Witches (East). Surtr once destroyed the gods, and out of the entire incident only one god managed to harm him.
Surtr may be one of the most powerful being in existance, the fact that he went toe-to-toe with the current strongest S-class WH, and only retreated when another appeared is proof of at least that much. In addition he also attacked the Witch South, something that even powerful witches such as Neptis and Varete are cautious and/or frightened of is a further testiment. In addition Surtr once annililated all of the gods, and was only ever harmed by one. One should note that on some of these instances East has not given him any mana, as he apparently acted without her consent. Since Surtr defeated Vihyungrag his power level is definitely greater than 2 average S-class WH
Surtr can also teleport to all sources of fire in the world.
His skin is as hard as steel and he moves quite fast, despite being well over 15 feet tall. He is the father of all living flame and is incredibly strong, even without East giving him mana.
Surtr took attacks from powerful opponents such as Eunryu an S- class WH and South without getting a scratch however, South said that she did not hit Surtr that hard.
- In his true form, Surtr's face is surrounded by fire and power level increases significantly to point where he can quickly defeated Vihyungrang who's worth 2 S-class WH personnel who Surtr lost to in his sealed form.
- Sealed Form
- In his sealed form, without much mana, Surtr is still strong enough to destroy almost every opponent. The only two people who have ever been able to beat him in this form and force East to give Surtr mana are Vihyungrang and Varete this would then indicate that in his sealed form Surtr power is greater than an S-class WH but below or equal 2 S-class WH personnel since he lost to Vihyungrang in this form.
- His name is sometimes incorrectly romanized as either Surt or Sleuth.
- His name, Surtr, is a direct reference to the Norse gaint of the same name who was an enemy of the Asgardian gods and who wielded a flaming sword. He was the ruler of the realm of flames, Muspelheim, and as a result would've been one of the oldest beings in Norse mythology - given than Muspelheim and Jotunheim (land of the gaints) were the first of the nine realms to be created.